“I thought maybe he had gone off home by himself,” remarked Ted.
“And I thought maybe a big wave had carried him off,” said Mrs. Dent. “I thought he had been caught by the sea puss.”
“What’s the sea puss?” asked Janet.
“It’s what folks around here call the undertow,” explained Mr. Dent. “Did you ever stand in the edge of the surf, and feel the top of the waves running up the beach, and then some water, lower down, running back into the sea?”
“Yes,” answered Ted. “It makes a funny pull on your legs.”
“Well, that funny pull is the undertow, or sea puss,” explained the lighthouse keeper. “It is a current of water running beneath the top of the waves to get back into the ocean. Sometimes it is very strong, and carries even powerful swimmers out to sea. Often there is a strong sea puss when there are only small waves. You Curlytops want to be careful. And if you find there is a strong sea puss, or undertow, don’t stay in bathing.”
“We won’t,” promised Janet. “I’m glad Trouble wasn’t caught in the sea puss.”
“I rather be caught by a nellifunt,” murmured William.
Mr. and Mrs. Dent laughed, and then, telling Ted and Janet to keep careful watch over their little brother, the lighthouse keeper and his wife went back to the beacon while the Curlytops started down the beach for the cottage.
They told of their adventures, and Mrs. Martin warned Trouble not to go away again and hide as he had done.